Modified castor oil



MODIFIED CAS'E'OR H.-

Everett E. Gilbert, New York, N. IL,

gnor to Tide Water Associated Gil Company, Bayonne, N. 3., a corporation of Delaware No- Drawing. Application February 11, 1942. Serial No. 430,351

teams. (01. 260-4055)- This invention relates to modified castor oil compositions and methods of making the same. More particularly, the invention is concerned with the treatment of castor oil and certain of its are not suitable for purposes of the invention,

tures generated in'these engines, resulting in decrease in operating emciency thereof. It was then proposed to employ a mixture of castor oil and mineral oil in order to overcome these dis-' advantages while preserving the oiliness properties of the castor oil. Since castor oil is substantially insoluble in mineral oil, several methods were devised for increming its solubility; but all of these methods detract from the efficiency of the blend. It has been proposed to use blown castor oil as one solution ofthe problem, and as another the addition of certain solubilizers ,or substances mutually soluble in the mineral oil and castor oil has been suggested. These expedients were unsatisfactory because they either decreased the oiliness of the castor oil or caused formation of sludge or other objectionabledeposits in the engines.

The present invention is designed to overcome the previously encountered difiiculties and to provide a modified castor oil which is adequately soluble in mineral oil. Blends of this modified castor oil with mineral lubricating oil are characterized by excellent stability and oiliness characteristics, making them particularly desirable for use in the lubrication of modern engines. A special use resides in the lubrication of airplane engines during the "breaking in" period.

The process of the invention comprises'treating castor oil or similar hydroxy materials which may be derived therefrom, such as hydrogenated castor oil for example, with an alkyl phosphite. During the reaction an alcohol containing an alkyl group of the phosphite used is given ed, and phosphorus is introduced into the castor oil molecule. The final product thus consists of a particular modified castor oil containing combined phosphorus. While the invention includes use of various trialkyl phosphites capable of reacting in the manner stated to produce soluble castor oil reaction products, particularly good results are obtained by use of trialkyl phtnphites containing alkyl groups of relatively low numbers of carbon atoms. Tributyl phosphite, for example, is representative of the latter class. Esters of phosphoric acid, i. e., alkyl phosphatfes, or when castor oil is treated with such phosphates phosphorus is not introduced into the caster oil molecule in the manner oi this invention and the reaction occurring in practice of the inventiondoes not take place.

In general, it is necessary phosphlte reactant in amounts in excess of that which will react with the caster oil or other material to be solubilized. The proper proportions of reactants may vary depending upon the specific substances used but can be readily determined in particular cases. The following examples are illustrative of the practice of the,

invention and the accompanying oxygen absorption tests indicate the high degree of stability characterizing the compositions.

Example I 30 grams of castor oil were heated in a glass vessel with $5 grams of tributyl phosphite at a temperature of 225 C. for 30 minutes. Butyl alcohol distilled ofl during the reaction. The mass was first allowed to cool and was then heated in vacuo to a temperature of -170 C. to drive off unchanged tributyl phosphite and the remaining butyl alcohol. The reaction product was found to contain about 1% of phosphorus and was completely miscible with mineral lubricating oil.

12.5 grams of the reaction product so produced were dissolved in 237.5 grams of a Pennsylvania base solvent refined motor lubricating oil of S. A. E. 10 viscosity and the resulting composition,

- containing 5% by weight of the reaction product,

was subjected to an accelerated oxidation test to determine its'stability. 1

In the test the stability of the oil was determined by measuring the rate of oxygen absorption at constant pressure by a definite weight of oil.. The apparatus used was similar to that described by R. W. Dornte in Ind. 8: Eng. Chemisa try, vol. 28 (1936), pages 26 and 2'7, as comprised briefiy a closed circulatory system comprising primarily an absorption cell in which the oil sample was maintained at C. during the test, a calibrated reservoir containing oxygen, and a pump for circulating the oiwgen through the oil to use the trialkyl I during the test. The average rate oi oxygen absorption during the test run determines the relative stability of the oil by this test.

The mineral oil composition containing the modified castor oil product produced as in Ex- I ample I, after being subiected to this test for 23 hours, had absorbed 6500 c. c. of oxygen. The

average oxygen absorption rate over this period was therefore 239 c. c./hour.

A 250 gramsample oi the described mineral lubricating oil used in making the blend of Example I to which no addition had been made absorbed 50500. c. 01' oxygen in. 22 hours when tested in the same apparatus under identical conditions. The oxygen absorption rate oi the mineral oil alone averaged 229 c. c./hour.

In the above test a difierence of c. e. per hour oxyge'n absorption rate is 01' negligible significance, so that the comparative results obtained indicate that the composition of mineral oil and modified castor oil is of the same stability as the mineral oil alone. Since the latter is of relatively high stability, it follows that the resistance to oxidation of the product of this invention is high. v

- Example II 28 grams of hydrogenated castor oil having a molecular weight of 944 were heated as in Example I with 45 grams of tributyl phosphite to 200 C. Butyl alcohol was evolved. The mass was then cooled and heated in vacuo to 200 C. to drive of! unreacted trbutyl remaining butyl alcohol.

A solution consisting of 12.5 grams or the reaction product and 237.5 grams of the mineral lubricating oil described hereinabove was subjected to the above described oxygen absorption test for 22 hours. At the end of this period the composition had absorbed 2850 c. c. of oxygen, the oxygen absorption rate thus being 130 c. c./hour.

In this instance it is to be observed that the blend of mineral oil and hydrogenated castor oil reaction product showed improved stability over mineral oil alone as evidenced by the low rate of absorption as compared to the rate obtained in the case 01' straight mineral oil shown above.

asenoea absorb considerably more oxygen per unit of time when subjected to these conditions than do the products oi this invention. Relatively speaking, therefore, the latter products are of high stability, for despite the presence of the normally unstable castor oil structure the reaction products exhibit high resistance to oxidation.

phosphite and the I claim:

1. Method for producing a product soluble in mineral oil from a substance selected from the group consisting of castor oil and castor oil derivatives containing a hydroxyl group, comprisin: reacting said substance with an alkyl phosp te.

2. Method as described in claim 1, in which the stated phosphite contains alkyl groups having a relatively low number of carbon atoms.

3. Method as described in claim 1, in which the stated phosphite is a trialkyl phosphite.

4. Method as described in claim 1, in which the stated phosphite is tributyl phosphite. 5. Method for producing modified castor oil which comprises reacting castor oil with an alkyl phosphite under conditions eflective to introduce phosphorus into the castor oil molecule and produce a product soluble in mineral oil.

6. Method for producing modified castor oil which comprises reacting castor oil with a trialkyl phosphite to produce a reaction product 1 containing phosphorus, and an alkyl alcohol and removing the alkyl alcohol from said reaction product.

7. Method for producing a castor oil product soluble in mineral oil which comprises reacting EVERE'I'I GILBERT. 

